She also made two electronic transfers totalling £115,000, from her NatWest account to Sean White, who was jailed today.

How could it happen? It's a question I've been asked today by others, and one I've been asking myself for six months.

My mother had banked with NatWest and its predecessors for 61 years and was a customer of its Private Banking service - NatWest managed her life savings. She was a former bank employee and an RBS pensioner thanks to my late father's work there. His father worked for a NatWest predecessor. So discovering her spending habits was something of a shock to say the least.

As any son would, I contacted her bank as soon as I found the paper trail that led to today's case. I was told: "Unless Mrs Cornock told us she was the victim of fraud, there was nothing we could do."

NatWest told me that, like other banks, have a strict duty of confidentiality to other customers and could not have alerted family members to the pattern of withdrawals.

I questioned why a widow pensioner was given her first overdraft - of £5,000 - at the age of 76. NatWest said the overdraft facility was standard and it wrote to her - in July 2009 - to reduce the limit.

The bank promised to investigate my concerns last September. My mother had just been diagnosed with terminal cancer and I hoped to secure some peace of mind for her in her last months.

After six weeks, having heard little I asked the bank if contacting the press office would produce a quicker response. I was told: "No newspaper would be interested".

Journalists love a challenge, so I contacted the Observer and the Daily Mirror in the hope of getting some answers while my mother was still alive. It appears my news judgement is sounder than some who work in banking.

I questioned why the bank did not raise concerns over the sums involved, as they added up to more than the value of my mother's home. The bank told me that "no bank is able to know all these details for all its customers". My mother's home was insured by.....NatWest.

NatWest say their investigations revealed that counter staff carried out the checks required of any vulnerable customer withdrawing huge sums of money. Indeed, one staff member at Penarth went outside the branch with my mother to check she was not being followed.

The two payments to Sean White passed "due diligence" checks by the bank, which said it accepted my mother's assurances that they were to open a bond at HSBC (despite the cash going straight into White's account) and that they were to an accountant. (NatWest's personal tax service completed her tax returns each year - if she had an accountant, it was them).

Sadly, my mother died last November before NatWest completed their investigations.

NatWest have consistently denied any liability, but have (verbally) offered us £60,000 as a "goodwill gesture" which we have told them we are minded to accept as a way of moving on from this trauma that does not involve enriching lawyers.

As a BBC correspondent I strive to be fair and impartial in accordance with our Values. As a son writing a personal blog I am doing the same although you may not be surprised to learn that I have recently changed the banking habits of a lifetime.